The present invention relates to a new and improved construction of a correction device with a rolling tape tension on a gear grinding machine, especially a form grinding machine for spur and helical cylindrical gears, comprising tapes subjected to an initial basic tension at rest, these tapes being attached at one end to a rolling block, there occurring between the rolling block and such tapes a relative rolling action, with the tapes being attached at their other end to a tape stand which is movable to-and-fro, and at such tape stand intermediate pieces or tape clamps are mounted on a device or means which imposes an additional torque on the rolling block.
According to a prior art correction device of the fore-going type, as taught for instance in German Pat. No. 1,178,676, there is provided a device for imposing an additional torque on the rolling block, which is in the form of couplings which are only active in one direction and designed so as to exert a torque of pre-adjustable magnitude and duration in order to thereby impose onto the tapes additional stress or to stress relieve such tapes in order to equalize their strain or elongation. The torque must be so pre-adjusted that when grinding gears by the generating method a tooth flank is contacted by the reciprocating grinding wheel during both forward and backward generating strokes, even if the set depth of cut is very small. It is therefore intended to prevent that due to unequal elastic deformation of the generating mechanism, especially stretching of the rolling tapes in the one or the other direction because of the inertia and friction in the generating transmission or drive, the tooth flank is only ground during the forward or return stroke of the grinding wheel. For this purpose, an additional torque which is pre-adjusted according to practical experience can have the desired effect.
Another prior art device employed on gear grinding machines which are controlled with rolling block and rolling tapes contemplates either displacing the tape stand in rhythmic synchronism with the generating action, or in the same rhythm to increase the tension in the rolling tape on one side of the rolling block and to decrease the tension in the rolling tape on the other side of the rolling block, in order to correct the tooth flanks in the sense of tip or root relief. Significant in this regard are German Patent publication Nos. 20 59 521, 24 55 808, and 24 59 033.